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Microbiome Dynamics and Pathogen-Driven Impacts in Marine Mollusks: Insights From Oysters and White Abalone.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Microbiome Dynamics and Pathogen-Driven Impacts in Marine Mollusks: Insights From Oysters and White Abalone./
作者:	Kunselman, Emily.
出版者:	Ann Arbor : ProQuest Dissertations & Theses, : 2024,
面頁冊數:	144 p.
附註:	Source: Dissertations Abstracts International, Volume: 86-01, Section: B.
Contained By:	Dissertations Abstracts International86-01B.
標題:	Biology. -
電子資源:	https://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=31243259
ISBN:	9798383209332

Microbiome Dynamics and Pathogen-Driven Impacts in Marine Mollusks: Insights From Oysters and White Abalone.
Kunselman, Emily.

Microbiome Dynamics and Pathogen-Driven Impacts in Marine Mollusks: Insights From Oysters and White Abalone. - Ann Arbor : ProQuest Dissertations & Theses, 2024 - 144 p.

Source: Dissertations Abstracts International, Volume: 86-01, Section: B.

Thesis (Ph.D.)--University of California, San Diego, 2024.

Marine ecosystems are facing various threats, from population declines to diseases that impact their overall health. My dissertation investigates the complex interplay between microbiomes, pathogens, and environmental conditions in three distinct marine organisms: Olympia oysters (Ostrea lurida) in the Puget Sound, Pacific oysters (Crassostrea gigas) in San Diego Bay exposed to OsHV-1 SDB µvar, and white abalone (Haliotis sorenseni) afflicted by Abalone Withering Syndrome. The goal of combining and comparing these systems is to elucidate the crucial role of microbiota in understanding ecosystem and host health, including microbes' response to environmental variables and their interaction with pathogens. The first chapter focuses on the Olympia oyster, a native species in the Puget Sound that has experienced a substantial population crash. To assess the impact of eelgrass habitat and geographical location on oyster microbiomes, Olympia oysters from a single parental family were deployed at multiple sites, both within and outside eelgrass (Zostera marina) beds. Using 16S rRNA gene amplicon sequencing, I demonstrate that gut-associated bacteria differ significantly from the surrounding environment. Regional differences in gut microbiota are associated with the oyster survival rates at different sites after two months of field exposure. However, eelgrass habitat does not influence microbiome diversity significantly. This research highlights the importance of understanding the specific bacterial dynamics associated with oyster physiology and survival rates in the Puget Sound.In the second chapter, I explore the OsHV-1 SDB µvar, a virus threatening oyster aquaculture globally, with a focus on its microvariant in San Diego Bay. The study investigates the influence of temperature on OsHV-1 SDB µvar infectivity. All microvariants of this virus exhibit limited replication and are unable to induce oyster mortality at lower water temperatures. Through experimental infections of hatchery-raised oysters at temperatures ranging from 15 to 24°C, I found that no oysters died at 15°C but most exposed oysters died above 18°C. The infection took hold faster at 21 and 24°C compared to 18°C. As oysters are often immunocompromised by this viral infection, I also chose to focus on the potential contribution of secondary bacterial infections to the disease. The microbiome of healthy, sick and dead oysters was compared using 16S rRNA gene amplicon sequencing to determine how the microbiome is disrupted by infection and which bacteria may be responsible for further progression of the disease. There is a clear shift in microbiome composition and decreases in evenness following infection with OsHV-1 SDB µvar. The third chapter centers on Abalone Withering Syndrome, characterized by the intracellular parasite Candidatus Xenohaliotis californiensus (CaXc) which disrupts gut morphology leading to starvation and possible death. Investigating the microbiome in endangered white abalone exposed to CaXc over an 11-month period reveals dynamic variations in the fecal microbiome and its distinctiveness from the internal tissue microbiomes. CaXc exposure notably impacts the anterior region of the digestive tract more than the distal tissues and feces, sometimes representing up to 99% relative abundance in the post esophagus samples. This comprehensive analysis incorporates qPCR to quantify pathogen loads over time and feces and in internal tissues. The pathogen is detected after 5 months of exposure and is most abundant in the post-esophagus tissue. The samples with the highest relative abundance of the pathogen were also shotgun sequenced to generate whole genome assemblies of bacteria. This led to the novel assembly of a 90% complete genome for CaXc, which is deposited in a public database. To pair these data with a more holistic understanding of the impact of this pathogen, RNA sequencing data was analyzed for differential gene expression patterns between exposed and unexposed abalone. While functional annotation and prediction was poor on the de novo assembled transcriptome, clear differences exist in gene-level response to CaXc between post esophagus and digestive gland tissue.

ISBN: 9798383209332Subjects--Topical Terms:

522710
Biology.
Subjects--Index Terms:

Marine ecosystems

Microbiome Dynamics and Pathogen-Driven Impacts in Marine Mollusks: Insights From Oysters and White Abalone.
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